Steering mechanism



Oct. 13, 1953 FRYSTAK 2,655,328

STEERING MECHANISM Filed Aug. 8, 1951 5 Sheets-Sheet 2 RIGHT B5 g ELEVON 2 E SERVO BY LEFT Z Z WIT RELAY L12 215%? M if ATTORNEY 49 51 $2 77 45 GYRO' I INVENTOR- l THEODORE K. FRYSTAK Oct. 13, 1953 T. K. FRYSTAK STEERING MECHANISM 3 Sheets-Sneet 3 Filed Aug. 8, 1951 2257 1 wA w YAW RATE GYRO INVENTOR. THEODORE K. FRYSTAK MKM ATTORNEY Patented Oct. 13, 1953 2,655,328 STEERING MECHANISM Theodore K. Frystak, St. Louis Park, Minn., as-

signor to Minneapolis-Honeywell Regulator lis', Minn., a corporation Company, Minneapo of Delaware Application August 8, 1951, Serial N0.24'0;863

11 Claims. (Cl. 244- 77) This invention pertains to steering mechanisms for dirigible craft and particula'rli to steering mechanisms for an aircr'aft of the flying wing yp Afr aircraft of this type is provided with a pair of elevon control surfaces with an elevon located in the trailing edge of the left and right wings of said craft. Both elevons are operable together in two ways; in one case they may be moved about their supporting axis in the same direction toact as elevators and in the other case may be rotated about their supporting axis in opposite directions to act as ailerons. 'The craft also includes two rudder surfaces with a rudder arranged in each of the left and right wings at'the trailing edge and adjacent the corresponding elevon. Each rudder consists of two hinged portions. These'portions when a rudder is actuated rotatein opposite directions away-from the trailing edge and out of the normal contour of the wing and are intended to merely increase the drag of the left or right wing. The craft with its control surfaces may thus be similar to that adapted to be controlled by apparatus disclosed in a U. S. patent application of Robert J. Kutzler, Serial No." 212,345; filed February 27, 1951. A flying wing aircraft as equipped with appa- 'ratus in the aforesaid application of Robert J. Kutzler tended to gain altitude when the craft was in a banked turn, due apparently to a nose up attitude assumed when placed in the banked turn. It Was found that this nose up attitude resulted from operation of a rudder of the craft during initiation of such turn even though the rudder had two portions oppositely positioned when the rudder was operated and was intended merely'to increase the drag or'resistance of the wing supporting said rudder. This'increase in altitude, it is believed, is occasioned by the greatereffect of the upper portion of the rudder than the lower on the flight attitude of the aircraft. This tendency to gain altitude is also prescut when the rudders are operated in straight and level flight in response to oscillations of the craft about the direction of flight sensed by a rate of turn gyroscope which operation increases directional stability. These oscillations are inherent in the structure of the craft. The pres- .ent invention is provided to automatically correct'forthe apparent aerodynamic differences of thetwo portions of the rudder which differences causes the gain in altitude in a banked turn and straight and level flight Th P y j c t er rqr of this invention is to'prevent such an altitude gain and to this end it is proposed to sense the rate of turn of a flying win aircraft in response to elevon and rudder operation and to operate in accordance with the rateof turn the elevon control surfaces downwardly to prevent gain in altitude by said craft during a banked turn.

It is an object of this invention to automatically apply a control effect to an elevon surface of a flying wing aircraft during heading turns of said'craft to prevent gain in altitude thereof.

Itis a further object of this invention to introduce a control effect on a control surface for changing the pitch attitude of an aircraft downwardly during displacement of a rudder of said craft.

It is a further object of this invention to provide a flying wing aircraft having elevon and rudder control surfaces arranged in the wings with a device for sensing rate of changes in heading resulting from rudder operation and a device for sensing bank angles due to opposite rotation of said elevons and for controlling rotation of both said elevons in the same direction in accordance with the differential effect of both of said devices.

It is a further object of this invention to oper ate the rudder and elevon control surfaces arranged in the wings ofa flyin wing aircraft initially to cause a banked turn of said craft and to cause further operation of said elevons in the same direction in response to the difference of the rate of turn of said craft and the bank angle of said craft.

It is a further object of the invention to introduce a control effect due to banking of an aircraftand a control effect due to rate of heading changes of said craft, said effects being of opposite sense and operating a control surface tending to change pitch attitude of said craft from both said control effects. The above and further objects of the invention will be apparent upon consideration of the following detailed description and drawing disclosin a preferred embodiment thereof.

In the drawings: Figure 1 in general is a functional arrangemnt of the invention, and Figures 2a and 21) together constitute a schematic arrangement of the novel steering mechanism for a flying wing aircraft.

f This invention is an improvement in the automatic pilot disclosed in the aforesaid application of Robert J. Kutzler, Serial No. 212,345, filed February 27, 1951. Referring to Figure 1 herein, the present arrangement like the prior arrangement of Robert J. Kutzler referred to includes a right elevon servomotor H and a left elevon servomotor I2 for operating the elevons (not shown) but which are positioned in the trailing edge of the all Wing aircraft, one elevon being arranged in the left wing and the other being arranged inthe right wing. The servomotors l i and #2 may be controlled to operate both elevons together in the same directions or may be controlled to operate them in opposite directions. When operated in the same direction, the elevons effect a turning moment about the pitch axis of the aircraft but when operated in opposite directions effect a turning, moment about the roll axis of the aircraft. The right elevon servo.- motor I i is reversibly controlled through an engage relay i3 (Figure 2a) by an amplifier 14. The amplifier I4 is of the A. C. discriminator type being supplied with an alternating current signal voltage and being also connected to an alternating current power source. The direction of rotation of the servomotor H depends. upon the phase relationship of the alternating current control signal to the alternating current power source. When the two voltages are in phase the. motor l! rotates in one direction and when the voltages are 180 out of phase the motor rotates in the opposite direction. The amplifier may be such as disclosed in Patent 2,425,733 tov Willis H. Gille et al. dated August 19, 1947. While the servomotor it may be of the type having a continuously running motor selectively coupled by clutches to opposing sun gears of a mechanical differential whose planetary arm is connected to acontrol surface, such as disclosed in the aforesaid patent to Willis I-I. Gille et al., it is preferably of the type which is used to actuate the rudder mechanism to be described in this invention.

The left elevon servomotor I2 is reversibly controlled through an engage relay i5 by a left elevon amplifier H6. The amplifier i6 and the servomotor l2 correspondrespectively to amplifier i4 and servomotor ll for the right elevon. The control of the right elevon servomotor ll by its amplifier It is the reverseof that of the left elevon servomotor i2 by its amplifier It so that when unlike control signals are applied to the amplifiers l4 and it the servomotors H and i2 rotate in the same direction to move their elevon control surfaces in the same direction whereas when control signals of opposite polarity are applied to the amplifiers i4 and 16 their servomotors i l and I2 are operated in reverse directions to move the elevon control surfaces in opposite directions.

. Signals of opposite polarity for the two amplifiers are obtained from an elevator function network 23 whereas signals of the same polarity are obtained from an aileron function network I28.

The elevator function network 2,0 includes sources of control signals and comprises a composite craft pitch attitude signal generator 2| and a craft bank attitude ,up-elevator signal generator 2-3; a craftyaw rate down-elevon signal generator 43; a pitch trim signal generator '51; and a craft pitch rate signal generator 62.

The aileron function network [20 includes sources of control signals and comprises a roll trim signal generator l2 i,'a composite craft heading generator i253 and roll attitude generator I32, a heading reset generator I48, and a turn control generator I51. 7 r

The control signals on the amplifiers I4, I6 are balanced by signals from SEIVOHiotor oper- 4 ated balancing signal generators 34 and I06 respectively.

The two rudders (one of which is shown) are sequentially operated by rudder servomotors I95, 209. These motors are alternatively controlled by an amplifier 226 of the A. C. discriminator type- Control signals for amplifier 225 are obtained from, a rudder network 243.. Network 249 comprises a craft yaw rate generator 24l, trim generator 249, craft heading generator 262, yaw reset generator 21?, servomotor operated composite reb'alance generator 288 and a portion of aileron function network I28 consisting of generators I32, I48, [51.

Reverting to. pitch function network 28, for the following detailed description of the invention to be considered with Figures 2a. and 2b,

pitch attitude signal generator 2| consists of a potentiometer having a resistor 23 and a slider 24 adjustable from the midpoint of said resistor in either direction. Resistor 23 is connected across the ends of a. secondary winding 25' of a transformer 2.? having a primary winding 26. The craft bank attitude up-elevator signal generator 28 comprises a potentiometer 29 havin a'resistor 30 and a slider 31. One end of resistor 3G is connected in series with additional resistors 32 and 33 to one end ofsecondary W n n 2 f transformer. 21, and the opposite end of resistor 33 is .connected to the remaining end of secondary winding 25. Signal generator 29 also comprises an up-elevator coordination potentiometer 28 having a resistor 35 anda slider 36. One end of resistor 35 is connected to the junction of resis'tors 30 and 32 and the opposite end of resistor 35 is connectedto the. adjustable slider 3!. The same primary winding through a plurality of secondaries. may be the energy source also for the additional generators to be described.

A conductor 31 extends from slider 24 of the pitch attitude signal generator 2! to a terminal 38. Slider 24 is adjusted along resistor 23 by a suitable operating connection 43 extending from a vertical gyroscope 39. The vertical gyroscope is of the type well known in the art having a rotor with threedegrees of angular freedom. The spin axis of the rotor is vertical and the casing supportingthe rotor in vertical position is crosstrunnioned in a gimbal ring support to provide ro.-. tation of the casing about two respectively horizontal axes. The vertical gyroscope 39 is so ar-.

' ranged in the aircraft that upon movement of the aircraft aboutthe pitch axis slider 24 is moved relative to resistor 23.

slider 3| is adjusted along resistor 30 by a suitable operating connection 48 extending from the vertical gyroscope 39. The operating connection 4| is adjusted whenever the craft moves about its roll or bank axis. The arrangement is such that with the craft in level position, rotatioh of the craft in either direction about its roll axis will cause the operating connection 4! to move slider 3! only to the right along resistor 30 so that the phase "of the signal is the same irrespective of the direction of roll.

Yaw rate down-elevon signal generator 43 positioned at lower right Figure 20. .comprises a potentiometer 44 having a resistor 45 and a slider 46; a secondary winding 41 of transformer 21; and a voltage dividing potentiometer 53 comprising a resistor 5| and a slider 52. The two ends of resistor 45 are connected to a common end of secondary winding 41. A center tap of resistor 45 is connected by conductor 49 to the opposite end of secondary winding 41, One end of resistor 5| is connected to slider 46, and the oppositeend of resistor 5| is connected to the end of secondary winding 4T which is connected to the center tap of resistor 45 by conductor 49.

. A conductor 55 extends'from the center tap conductor 49 to slider 35. Slider 46-is positioned along resistor t5 by means of a suitable operating connection 54 from a yaw rate gyroscope 53. Gyroscope 53 is of the type whose rotor has two degrees of angular freedom with angular movement about one axis restrained. The rotor rotates about a horizontal spin axis in a gimbal ring which is trunnioned about a horizontal axis at right angles to the rotor spin axis with means for restraining precession of the gimbal ring about said last named axis. The arrangement is such that as the craft rotates aboutits'vertical axis the slider is is positioned relative to the center tap of resistor 45 in one or another direction depending upon the direction or turn and the extent ofsu'chdis'plac'ement depends-upon the rateof turn. It will be evident; however, due to the specific connections of resistor 45 to secondary 4'! that the phase of the signal obtained from signal generator 43 is the same irrespective of the direction of turn.

Trim signal generator 5? consists of a potentiometer having a resistor '58 and a slider 59; and resistor 58 is connected across a secondary winding 60 of transformer 21. Slider 59 may be manually adjusted along'resistor 58. A conductor 56 extends from slider 59 to the manually adjustable slider 52 of voltage divider 5Q.

Pitch rate signal generator 52 compries a potentiometer 63 having a resistor 6d and a slider 65; a pitch rate coordination potentiometer 5'! having a resistor 5'3 and a slider and a seccndary'BB of transformer 27; Resistor 6d is connected across the ends of secondary winding 66. Resistor 63 is connected across a center tap of secondary winding 55 and slider 55;

A conductor 80 extends from the center tap of secondary winding 66 to a center tap of secondary winding Bil of the trim signal generator 51. Slider 65 is positioned along resistor 64 through an operating connection 82 from a pitch rate gyroscope 8!. to yaw rate gyroscope 53 but is mounted "differently in said craft and has a'rotor freely rotatable in a gimbal ring about one axis and the gimbal ring in turn being trunnioned on an axis at right angles to the rotor spin axis-in a'support. Procession of the rotor about the trunnion axis may be restrained by spring means, convention: ally' used. The rate gyroscope 81 is so arranged in the aircraft that the slider 55 is moved with respect to resistor 64 in proportion to the rate of pitch of the aircraft and in a direction depending on the change in pitch attitude. The slider 69 may be manually positioned or adjusted along resistor 68 to select a desired ratio of the rate signal from generator 63 but once adjusted is generally so retained.

It is evident that the aforementioned signal generators are connected in electrical series relation so that the signals provided by the gen erators may be algebraically added and a resultant signal provided. This resultant signal appears between slider 69 of pitch rate signal generator 82 and terminal 38 connected to slider 24 by conductor 31. An elevator'ratio voltage divider H is connected between sliders!) and terminal 38. This voltage divider it ocmp'rises' a fixed'resistor l2 and an adjustable resistor 13 having a resistor 15 and aslider 74. Thetwo re- The pitch rate gyroscope issimila'r sis'tors 15 and 12 are connected in series with the remaining endof resistor 12' connected to terminal 38 and the remaining end of resistor 15 being connected to slider 69. Slider M is manually adjusted along resistor 15 so that the voltage actually derived from the network 20 for providing an elevator action is obtained between adjustable slider 14 and terminal 38. Conductor 10 connects slider 14 to a terminal 19.

A voltage divider 'liconsisting of fixed resistors l1 and 18 is connected between the signal generator output terminals 38 and 19 of network 20. Resistors l1 and 18 are connected in series and are of equal value. Their junction for the moment may be considered at ground potential. It is evident that the difference of potential between terminal 38 and terminal 80 is opposite that-between terminal l9 and terminal 89. The difference of potential between terminal 38 and terminal 80 is used to control the operation of the"right elevon servo amplifier 14 whereas the potential between terminal 19 and terminal 89 is used to control the operation of the left elevon servo amplifier- 6. Although the voltage between terminals 38'Bfl is opposite to that between terminals l980, servomotors ll, 52 rotate in the same 'direction' on unbalance of network 29 by cross connecting one motor to its control amplifier with the other motor directly connected. -.The right servomotor amplifier I4 is provided with signal input terminals 85, and power input terminals 81, 8B. "Terminal 86 is connected to ground which for the present purpose may be considered as at the same potential as terminal 80. Between terminal 38 and the other amplifier input terminal 85 is a right elevon follow-up signal generator 84.

Signal generator 84 comprises a right elevon follow-up potentiometer 90 having a resistor 9| and a slider 92; a right elevon ratio potentiometer 93 having a resistor 94 and a slider 95; a secondary winding 96 of transformer 21, and a fixed resistor 91. Resistor 9| is connected across the ends .of secondary winding 95. Resistors 94 and 91 are connected in series and the remaining end of resistor 94 is connected to slider 92 and the remaining end of resistor 91 is connected to terminal 38. .A conductor I60 extends from terminal 38 to a center tap of secondary winding 95. A conductor llJl extends from amplifier terminal 85 to slider'95. Slider 92 is positioned along resistor 9! by a suitable operating or follow-up connection 98 from right elevon servomotor i I. Slider 95 is adjusted along 94 by means to be described.

potential between terminal 8!! and terminal 19 is used to control the left elevon servo amplifier IS. The amplifier it is provided with Signal input terminals I02, I33, and power input terminals I54, I65. Terminal 553 is connected to ground. Between terminal '32 and terminal to is a left elevon servomotor follow-up signal generator Hi6. Signal generator 85 comprises a left elevon servomotor follow-up potentiometer it? having a resistor I68 and a slider 1139, a left elevon ratio potentiometer H8 comprising a resistor I II and a slider H2, a fixed resistor H3, and a secondary winding Iii of transformer 21. Resistor I08 is connected across the ends of secondary winding |l1.- Resistors iii and H3 are connected in series and the remaining end of resistor ill' is connected to slider Hi9 and the remaining end of resistor H3 is connected to a centerv tap of secondary winding ill by conductor H4. A conductor" I I5 extends -from, terminal 19 to the center tap of secondary winding II1. A conductor extends from slider Iii to in put terminal I92 of amplifier I9. Slider I59 is positioned along resistor I98: in accordance with the movement of servomotor I2 by a suitable operating connection H6; Sliders H2 and 95 may be manually adjusted along their respective resistors I I I and 94 concomitantly by operating means The aileron action network I29, as stated, com prises an aileron trim signal generator I2I; a composite heading responsive bank-craft roll attitude signal generator, Nil; a heading reset signal generator 58; and a manually operable turn control signal generator I51. Signal generator IZI includes a, potentiometer having a resistor I22, a slider I23 and a secondary winding I24 of transformer 21.- Resistor I22 is connected across the ends of secondary winding I24 and the slider I23 is positioned along resistor manually. Generator I3! includes a heading control potentiometer I25 comprising a resistor I26 and a slider I21; an adjustable resistor I35; a voltage dividing potentiometer I39; a secondary winding I36 of the transformer 21; a craft roll attitude potentiometer I32 having a resistor I33 and a slider I34; and a turn control coordination, potentiometer I43 having a resistor I44 anda slider Hi5. Resistor I26 is connected across the secondary winding I36. Variable resistor I35 and voltage dividing resistor I31 are connected in series and the remaining and of resistor I35 is connected to slider I21 and the remaining end of resistor i3? is connected to acenter tap of secondary winding I39. A conductor I49 extends from slider E23 to manually adjustableslider I38; Slider :21 is positioned along resistor I26 through an operating connection PM from a heading responsive device This heading responsive device may be a conventional directional gyroscope of the type well known in the art having its rotor supported in a casing for rotation about a horizontal spin axis with the casing in turn carried in a gimical ring about a horizontal axis at right angles to the rotor spin axis. The gimbal ring in turn is rotatably carried about a vertical axis. The arrangement is such that upon change in heading of the craft, slider I21 isdmoved relative to resistor I26. The gyroscope I92 is provided with a caging or locking means for preventing movement of slider I21 by said gyroscope during manually initiated changes in heading.

The resistor I33 of roll attitude potentiometer I32 is connected across the secondary winding I35. Resistor I49 has one ,end connected to slider I34 of potentiometer I32 and its opposite end connected to a center tap of secondary winding I39. The slider I34 isposiitoned along re-' sistor I33 by means of a suitable operating connection I45, 4| from the vertical gyroscope 39 in accordance with the bank attitude of the aircraft. Slider I34 is displaced from the center point of resistor I33 in one or another direction depending upon the direction of bank of the craft.

Reset signal generator I48 has a resistor I49 with one end connected directly to a secondary winding I52 and its opposite end connected to one end of a variable resistor II Whose opposite end is connected to the remaining end of secondary winding I52. A ratiopot'entiometer has a resistor I54 connected across a center tap of secondary winding I52 and slider I59. A conductor I56 extends from the center tap of sec- 8 ondary' winding I52 to slider I34. Slider I59 is positioned along resistor I49 by a reset motor more fully disclosed in the aforesaid Kutzler application to cause the. craftto hold heading despite any continuous disturbing force tending to change heading.

Manual turn signal generator I51 comprises a pilots turn control potentiometer I53 having a resistor I59 and a slider I66; a co-pilot or remote turn control potentiometer I62 having a resistor I63; anda sliderlt i; a secondary winding I61 of transformer 21; a secondary winding I68 of transformer 21; and a fader potentiometer I65 having a resistor I66 and a slider I61. Resister I 59 is connected across the secondary winding I6I. Resistor I63 is connected across the secondary winding I68. Resistor I66 of the fader potentiometer is connected across the sliders I69 and I64. A conductor I18 extends from slider I61 of the fader potentiometer to adjustable slider I55. Sliders I69 and I64 may be manually adjusted along their respective resistors I59, I63. A conductor I1I extends from a center tap of secondary winding I6I to ground terminal I11. A conductor I19 extends from a center tap of fader potentiometer resistor I66 to the center tap of secondary I6I. A conductor I86 extends from the center tap of resistor I63 to ground terminal I11. It is evident that the left portion of the fader potentiometer serves as a voltage divider for the pilots turn control potentiometer I58 whereas the portion to the right of the center tap of the fader potentiometer resistor I65 serves as a voltage divider for the co-pilot turn control potentiometer I62.

An aileron ratio potentiometer or voltage divider is provided for network I23. This voltage divider I12 comprises a voltage dividing potentiometer I13 havinga resistor I14 and a slider I15 and a fixed resistor I15. Resistors I14 and I16 are connected in series and the remaining end of resistor I14 isconnected to a center tap of secondary winding I24 of the trim signal generator IZI and the opposite end of resistor I16 is connected toground terminal I11. A conductor I82 extends from slider I15 to terminal ofnetwork ZIl. I

Passing to Figure 21 there is shown an arrangement foroperating the two rudder control surfaces for the aircraft with a portion I35. of one wingof the aircraft shown in section. This View of thewing shows the two oppositely rotatable portions I86, I81 of the rudder in full line in normally closed position. The dotted lines indicate the respective position of the portions of the rudder whenmovedtoward operated position.v The. pivot portions ISfi, I31 may be operated by their respective links I83, I99 connected to a longitudinally movable rack bar I99. The bar may be driven by its engaging pinion I9I carried byan outputshaft I92 of one of the rudder servomotors. While but one rudder is illustrated, the other is of the same configuration. The output shaft I 92 is connected by a suitable magnetic clutch I93 to a drive shaft I94 of a rudder servomotor I95.

The motor I95 is of the D. C. type having field windings I96, I91, a pulsing, clutch I98 and an armature I 99. The field windings, pulsing clutch winding I98 and armature are so interconnected that with either field winding energized the pulsing clutch and armature are also energized. The pulsing clutch I98 is the type'which when u'n energized holds the drive shaft I99 in braked condition but when energized serves to couple the armature I99 to the drive shaft I94. Such type of arrangement is old in the art as evident in Lear 2,267,114. The other rudder motor 200 similarly includes field windings 20I, 202, pulsing clutch winding 203, armature 204, drive shaft 205, magnetic clutch 206, and output shaft 201.

Rudder motors I95, 200 are operated in sequence. This sequential operation is controlled by relays 208, 2 i3 of the single-pole, double throw type. Relay 208 includes an operating coil 209, an arm 2I0, an in contact 2I2 and an out contact 2| I. Relay 2I3 includes an operating winding '2I4, an arm 2I1, an in contact 2I5, and an out contact 2I6. Winding I96 of motor I95 is connected to in contact 2I2." Winding I91 is connected to out contact 2I6 of relay 2I3; Winding I of motor 200 is connected to out contact 2 of relay 208 and winding'202' of motor 200 is connected to in contact 2l5 of relay 2I3.

The energization of operating coil 209 of relay 269 is controlled by a limit switch 220 operated from the output'shaft' 201 of motor 209. The energization of operating coil '2I4 of relay 2I3 is controlled by a limit switch 22I operated from the output shaft I92 of motor I95.

Since, as shown inthe section of the wing, the rudders may be moved from a closed position toward an open'position the switches 220 and 22I are so operated by the output shafts 201, I92 to be normally in the closed (full line) position with its rudder closed; As a motor operates its rudder toward an open position, the switch 220 or 22I operated by its output shaft or spring biased moves to open (dotted) position. Thus the relay arms 2I0, 2 I1 are shown in their operated position and biasing means 222, 223 are illustrated for moving the relay arms 210, 211 to their unoperated or out position when the respective circuits are opened to operating coils 208, 2I3.

With relay arm 2I1 connected to a source of direct voltage, its engagement with in contact 2I5 calls for rotation of motor .200 to open its rudder whereas engagement of arm 211 with out contact 2I6 calls for operation'of motor I95 to close its rudder. With relay arm 2I0 connected to a direct voltage source, its engagement with in contact 2I2 calls for operation of motor I95 to open its rudder whereas engagement of arm 2I0 with contact 2 calls for operation of 200 to close its rudder. Arms 2I1, .2I0 are connected to a source of direct voltage through the outputof an amplifier 226 through their respective rudder engage relays 224, 225. The energization of relays 224, .225 is controlled from a manually operable single pole single throw switch 221 which concomitantly energizes the magnetic clutches I93, 206. The single pole single throw switch 21 may be arranged to concomitantly energize elevon engage relays I3, I5, Figure 2a, and corresponding magnetic clutches for motors II, I2. 7

Returning, amplifier 226 is of the A. C. dis criminator type. The amplifier 226 includes A. C. signal input connections 228, 229 and A. C. power input connections 230, 23I. The amplifier 226 includes relays232, 233 which are alternatively operated depending upon the phase relationship of the A. C. signal-input voltage with respect to the power input voltage. For simplicity, relays 232, 233 are indicated ashaving a single arm and single in contact. Engage relay 224 is connected to the in contact of amplifier relay 232 and engage relay 225 is connected to the in contact of amplifier relay 233." The relay arms are connected to a D. C. busbar 234 supplied with power from a battery 235 or other suitable source.

With both rudders in the closed position so that both relays .208, 2I3 are operated, the closing of amplifier relay 232 will transmit D. C. voltage to winding 202 of motor 200 causing it to rotate its rudder toward open position. This rotation immediately opens switch 220 causing the deenergization of relay winding 209 and movement of arm 2I0 against out contact 2. If thereafter the other amplifier relay 233 is energized, winding 20I of motor 200 is energized to move its rudder toward closed position. At the instant ofclosing of its rudder, switch 220 is closed and relay 208 becomes operative. Further continued energization of amplifier relay 233-results in energization of winding I96 of rudder motor I thereby causing the other rudder to be moved to open position opening also switch 22I. Subsequent energization of amplifier relay of 232 causes the energization of winding I'91'of motor I95 whereby the operated rudder is moved toward closed position. It is thus evident that sequential operation of the two rudders is obtained.

Reverting to amplifier .226, the control signal applied to terminals 228, 229 is derived from a balanceable control network 240. Network 240 includes in review a yaw rate signal generator 24I, a rudder trim signal generator 249, a heading control signal generator 262, a yaw reset signal generator 211, a servomotor follow-up signal generator 288, and in the'aileron network I20 the turn control coordination potentiometer I43, the voltage dividing potentiometer I53, and the manual turn control network I51.

Signal generator 24I comprises a potentiometer having a resistor 242 connected across a secondary winding 244 of transformer 21 and a slider 243 positioned along resistor 242 by a suitable operating connection 245 from a yaw rate gyroscope 246. The yaw rate gyroscope 246 is of the conventional two degrees of angular freedom type of gyroscope with restraint applied to angular movements about one axis. Slider 243 is moved along resistor 242 from the center point thereof in one or another direction depending upon the direction of the turn and in an amount depending upon the rate of turn. A conductor 241 extends from the input connection 228 of amplifier 226 to slider 243. Trim signal generator 249 comprises a potentiometer having a resistor 250 and a slider 25I with the resistor connected across a secondary winding 260 of transformer 21. The slider 251 is manually adjusted along resistor 250. A conductor 25I extends from a center tap of resistor 242 in the rate signal generator to a center tap of secondary winding 260.

Heading signal generator 262 includes a heading detecting potentiometer 263 having a resistor 265 and a slider 266; fixed resistors 268, .269, a secondary winding 261 of transformer 21, and a voltage dividing potentiometer 210 having a resistor 212 and a slider 213. One end of resistor 265 is connected in series with resistor 268 to one end of'secondary winding 261 and the opposite end of resistor 265 is connected in series with resistor 269 tothe other end of secondary winding 261. The resistor 212 of voltage dividing potentiometer 210 is connected across a center tap of secondary winding 261 and slider 266. A conductor 214 extends from slider 25I of signal generator 249 to a center tap of secthe amplifier 226 operating, through its relays 232 or 233, servomotors I95 or 200. The operation of either motor results in a follow-up movement of slider 29I or 296 to balance and limit the amount of movement of the servomotor in accordance with the movement of the slider 25I. Similarly the heading responsive device I42 controls the motor in proportion to heading changes.

The operation of the elevons and rudder control surfaces may be effected simultaneously from the manually operable turn control network I51 or heading responsive device I42. With the slider I61 of the fader potentiometer I65 toward the left from the mid-position and considering a manually controlled turn, operation of slider I60 of the pilots potentiometer I58 causes a signal potential to be derived between slider I60 and ground terminal I'll. This-signal voltage is applied through the heading reset signal generator I48 and turn coordination potentiometer I43 and conductor 3l3 and the portion of network 240 shown in Figure 2b to the rudder amplifier 226 to effect rotation of one or the other of the servomotors. The follow-up action of the rudder servomotor develops a potential between slider 300 and the unoperated follow-up slider which is equal and opposite to the signal from the pilots potentiometer I58.

The signal from the pilots potentiometer I58 also appears across voltage divider I6 and is applied at terminal 80. The voltage between terminal 80 and ground terminal I1! is thus applied to both elevon amplifiers I4 and I6 causing the rotation of the right and left elevons in opposite directions.

The operation of the pilots slider I60 is accompanied by the rendering of the operation of the slider I21 and 266 ineffective by the heading deviation means I42 in a manner similar to that shown in a prior application of Robert J. Kutzler, Serial No. 14,787, filed March 13, 1948. Since the presence of the arrangement for preventing operation of sliders I21, 266 is not necessary to an understanding of the present invention, it has been omitted for the purpose of clarity.

The operation of the pilots potentiometer slider I60, as stated, in effecting elevon and rudder operation, will cause the aircraft to gointo a banked turn or if the heading responsive means I42 senses a change in the heading of the craft, the signal will be placed in a banked turn, as previously explained, to restore the heading of the craft to the desired one. The vertical gyroscope 39 by operating slider I34 supplies signals to network I20 and 240 so that the elevon and rudder are moved to unoperated position. It has been found desirable in such turn to provide generally an up-elevator signal in proportion to the magnitude of bank of the aircraft to prevent loss of altitude in such turn. This signal comes from the up-elevator signal generator 29.

During the entry into the turn, however, as distinguished from the steady state portion of the turn, the craft has a tendency to increase in altitude rather than merely maintain its altitude from the up-elevator signal generator.

It will be noted that in the construction of the rudder, see Figure 2b, the two hinged portions, I86, I81 apparently are displaced equal angular amounts from their respective closed positions during operation of a rudder servomotor to effect merely an increased drag on its wing. It appears, however, that the upper portion of the rudder surface has a greater effect than the lower portion of theoperated rudder. Thus the upper portion I86 tends'to rotate the craft about its pitch axis in an upward attitude from trailing edge to leading edge so as to tend to cause the craft to climb.

In order to offset this tendency to change attitude during operation of a rudder, the signal generator 43 previously described has been provided in the pitch function network 29 to effect a compensating operation of the elevon control surfaces of the aircraft. Thus when either one or the other of the aircraft rudder control surfaces is operated to cause a turn of the craft about its vertical axis the yaw rate gyroscope 53 responds to the rate of turn set up and provides a signal from the signal generator 43 so that the elevons are moved in a downward direction to compensate for the tendency of the upper portion of the operated rudder surface tending to cause a change in attitude.

With the present arrangement, as the aircraft enters a turn at which time its rate of turn caused by the rudder is greater than the corresponding bank angle required for coordination, the yaw rate gyroscope signal generator 43 provides a down elevon signal in excess of the up-elevator signal from generator 29 to prevent gain in altitude during entry. After the aircraft is in the steady state portion of the turn which is now coordinated and with the rudder returned to normal position, the rate of turn is proportional to the bank angle. The up-elevator signal during the steady state portion of the turn which is obtained from signal generator 29 in network 20 is greater than the down elevon signal from signal generator 43 so that the net elevator position of the elevons is in an upward direction tending to maintain altitude during the turn. Thus, it is evident that while the initial yaw rate is such as to permit a down elevon signal during turn entry yet during the steady state or coordinated portion of the turn, a net upelevon position is obtained to prevent loss of altitude.

It will now be apparent that there has been provided novel apparatus for compensating for the difference in aero-dynamic effects of the two portions of a rudder which has a net result of providing a moment about the turn and pitch axes of the aircraft by opposing the turning moment about the pitch axis by a counter moment derived from positioning of the elevon control surfaces having a moment about the pitch axis, so that the aircraft tends to maintain altitude during entry into and during the steady state portion of a bank turn.

What is claimed is:

1. Control apparatus for an aircraft having elevon control surfaces operable together in the same or alternatively in opposite directions to exert moments about the pitch or roll axis of the craft and having a pair of rudders sequentially operable, each rudder having two portions t hich are arranged to swing outwardly transversely from the wing surface of said aircraft in opposite directions, from the trailing edge of the wing of said craft an operated rudder exerting a moment about the vertical axis and a moment about the pitch axis, said apparatus comprising: motor means for operating said elevons; motor means for operating said rudders; heading control means having connections for operating said elevon motor means and said rudder motor means to oppositely move said elevons and position a rudder to place said craft in a banked turn; means responsive to rate of turn of said craft about its acetate rtic'al aids; responsive to fbarikof sai'd craft; and in'eaiis for furtherfoperating'both s'aid elevons in th'e same diretion afidcontrdlied' from said rate of turn and saidobank 'responsivefi'n'eans.

"2. The apparatus claim *1, with follow-up 'rneansoperated "by said elevoh inotor means and said rudder :mdto'r means iforflimiting opeia io'n thereof proportional tooperation' of said heading control means.

'3. Control apparatus for an faircr'aft 'leilons Operable the same "*dr alternatively opposite directionstoxeit momentsei-theisweat the pitch or roll "axis of "the craft iespectivelyfahd "a f'rii'd'der consisting of two portions hinged *to swing eutwa'rdi jfrom the traiiing edge of the wiri'g of said craft "to exert ino'nientsfabcut the Vertical "and pitch axis of the craft, said apparatus comprising; semttivemeans Efor prodircing a signal corresponding with a des ired rate of t'u'rn 6f {said craft dperating levon' *rnotor nieans;

moment of the 'iHddFsui f ame atom; the piteh "the craft and connectedto bbthwcontrol'aneans :to c'ause opposite V movement'pf t 'saicl elevons and -movement ofsaid rudder to-i cause -'said craft-to --undergo a tanked turnfand ru'rtherineans -re- 1- sponsive to rate oi rotation of 'said craft; about its vertical axis for producing a' secorid' signaland connected to said elevon'contrbluneans to cause said elevonstomove downwardly to prevent gain in altitude by said; cr'aftduetothe moment of the rudder about thepi'tch axis.

' 5. Control apparatusgfor an aircrafv'havin two pairs of control surfaces arranged ,inthe trailing edge of the (wings "offsaid craft, said apparatus comp'risingz'jirneans for projecting. one control surface of one "of js'aid'rpairs Ifr'om'the plane of the wing .ab'outcanla'xis' f'solas' to receive on said surfaceflanimpa'ct ,of i-thelaifstream and thus. causesaidicraftItolt'urn about its vertical axis; means responsive to the rate of turn of the craft about said axis; "c'ontrol ineans"operated "by said rate'of turnresponsivemeansfand fur-" ther "means :operateot byfsaidfc'ontfol means for "moving" the "other "pair of "contr'oli surfaces in a downward'directi'on to exert amoment'ab'outtm craft pitch axisto prevent gaindnaltitudefiby "said craft front-an upward-moment by saw-one 16 7 surface due to the impact of the air-stream on said one control surface.

6. -Contro1apparatus for "an aircraft having a first control surface in one wing that produces a moment about the verticaland pitch axes of said craft "and a s'eoon'dancl third control surface in each mine that produce when operated in the same-direction a moment about the pitch axis and when operated"infoppositedirections produce a moment about-the roll axis, said apparatus comprising-means for 'operating sai'd first,-'second, a'nd thirdsurfaces from a "normal position to place said craft in "a banked turn; and ifurther "means responsive to rate "of turn ofsaid craft for additionally operating said second and third surfaces in the same diretion "-to -'oppose the moment of said operated 'first "control surface about the pitch axis.

7. Control --apparatus for an aircraft 1 having a first control surface arranged in a wing that produces a mom'ent about the craft vertical and pitch axes and a second and third control sur- 'f-ace' arranged in=the Wings cream craftandpro- 'duc'inga moment 5 about the craft -roll axis-when said second and -'-third surfaces are positioned in opposite directions and producing a -moment about the c'raftpitch axisWheHposi-tioned inthe same direction,saiclapparatus comprising: a-first control meansior operating said first-surface; a second 'controPmeans i'for operating sai d second and third surfaces; signal means responsive to I change in heading and having connections for operating: both control means to place said cr-a'ft in a hanked turn; andfurther signal means .re-

sponsive to the movement of the craft-about-said vertical axis 1 an'd having connections for further :operating said Y second control means to cheat mov'ement of :said second andthird surfaces to pro'du'ce' a moment opposing: the moment of: said first surfacet about the pitch axis.

8. ncontrol apparatus" for :an aircraft having'a I firstcontrol sur-face'i'arranged in a winger said :craft that produces on-operation a desirable moment about the craft "vertical taxis-and -an undesirable moment fabout .the pit-ch ax-is Land :second a-ridlthifid control surface Iarranged in the wingsziofsrasaidicraiti and,producing-"moments about. the craft rolhaxis when saidsseoond and third surfacesr tare positioned ineopposite cdirections and producing amoments iabout :the craft apitch :axisiwhen positioned. in the sazneidirection; said apparatus comprising: raifirst; control means -for operating said first2surface; aisecoridlcontrol emeans for operatingssaid second .andthirdasur- 'facesyheading change means having connections ;for operatings'bothrcontrolmeans. to..eff 681110138113,- tion :of' saidthree surfaces-to tplaceasaid :craft in a-, -banked-. turn and turtherzmeans effective :by the: craft .movement :duringaoperation: of: said zfi-rst ;,s urf ace of or further coperatingc said second control means: to :eff ect additional imovementwf said-rsecond and; thi'1disuifaj 3Si-110E aproduce xmoments'about the pitch axis opposing..-the1moment about'g'thei pitchu-axisof said firStISu-fiace.

T 9. Control apparatus forearm; aircraft having .21 first :control surface arranged in swing oils-said craft that produces-on displacement from .a-nor- ,mal 'posit'ion; a (moment aboutiathe craft vertical *and pitch axes :and a secondand-third control sur face arrang-ed in the wings ofsaid craft and p'roducing moments about the ''craft ro1laxis w'irhen saidsecond and third surfacesare displaced from a normal position in'opposite directions'- and producing am'oment. about the craft pitch axis when'said surfaces are positioned from normal in the same direction; said apparatus comprising: a first control means connected for operating said first surface; a second control means connected for operating said second and third surfaces; means connected for operating both control means to effect operation of said three surfaces to place said craft in a banked turn; means responsive to the bank attitude of the aircraft for operating said second control means to effect operation of said second and third surfaces in an upward direction to maintain the altitude of the craft during said turns; and means for modifying the position of said second and third surfaces from said bank responsive means during entry of said craft into said turn.

10. Control apparatus for a flying wing aircraft having elevon control surfaces operable in the same direction for producing moments about the craft pitch axis and operable in opposite directions for producing moments about the craft roll axis and having a pair of rudders sequentially operable, each rudder having two portions which are arranged to swing outwardly transversely from the wing surface of said aircraft in opposite directions each rudder producing a moment about the craft vertical and pitch axes, said apparatus comprising: a first balanceable control means for operating said elevon surfaces; a

second balanceable control means for operating said rudder surfaces; selective means for unbalancing both control means to efiect operation of said elevons and one of said rudders to place said craft in a banked turn; further means responsive to the bank attitude of the aircraft for further unbalancing said first control means to efiect operation both of said elevon surfaces in an upward direction to maintain the altitude of the craft during said turn; and additional means for unbalancing said first control means for modifying the position of said elevons dictated by said bank responsive means during entry of said craft into said turn.

11. Control apparatus for an aircraft having elevon control surfaces together in the same direction and producing moments of the craft about the pitch axis and operable in opposite directions for producing moments about the craft roll axis, and having a pair of rudder control surfaces sequentially operable each rudder having two portions which are arranged to swing outwardly transversely from the wing surface of said aircraft an operated rudder exerting a moment about the craft vertical axis and a moment about the craft pitch axis, said apparatus comprising: a first control means including two motors for operating said elevon surfaces; a second control means including two motors for operating said rudders; heading change detecting means for operating both control means to effect operation of both elevon motors and one rudder motor to place said aircraft in a banked turn; and means effective during operation of said rudder by its motor and responsive to craft rate of turn for further operating said second control means to effect movement of said elevon surfaces in the same direction to produce moments about the pitch axis of said craft opposing the moment of said rudder surface about said pitch axis,

THEODORE K. FRYSTAK.

No references cited. 

